Gravel washer



F. R. DRAVO GRAVEL WASHER Nov. 12, 1929.

Filed-March 20, 1928 s Sheets-Sheet F. R. DRAVO GRAVEL WASHER Nov. 12, 1929.

Filed March 20, 1928 3' ShiEts-Sheet 2 INVENTOR F. R. DRAVO GRAVEL WASHER Nov. 12, 1929.

Filed March 20, 1928 3 Sheets-Sheet INVENII'OR Patented Nov. 12, 1929 FRANCIS R. nRAvo, or nnenwonrir, PENNSYLVANIA, 'AssienoR To THE, DRAVO con- TRACTING COMPANY, or PITTSBURGH, PENNSY VANIA, AcoRronA'rIon or PENN- V SYLVANIA GRAVEL WASHER -"cleansing sand and gravel taken from river beds and'other places of deposit, to make it suitable for use for building purposes. The object of my invention is an improvement in such a device,to affordrmore expeditious and more complete removal from the material dredged of its undesired contents of boulders and of silt and clay, leaving for further s'epa- 'ration the desired sand and gravel.

A gravel washer or scrubber embodying my invention is illustrated inthe accompanying drawings. Fig. I-is a diagrammatic view in {elevation of a sand and gravel plant in which is included the washer or scrubber of my in vention. II is a view in section, on the plane indicated at III-II, Fig. I. Fig. III is a view to larger scale, showing partlyin elevation and partly in axial section, the washer in which the invention centers. Figs. 'IV and V are'views in transverse section, on the planes indicated at IVIV*and V-V, Fig.III. I The various pieces of apparatus which make up a sand and gravel plant are-suitably placed and supported, with reference to the deposit to be worked. By way of example I show an arrangement suitable for work upon 'a deposit'which constitutes a riverbed, and accordingly'the plant includes a barge, upon which the washer may be understood to be supported. Other pieces of apparatus may be understood to'be supported on this or on adjacent boats, or elsewhere, as maybe convenient. at 1 and the barge which carries it, at 2. V

The-washer or scrubber is essentially an elongate structure here shown to be cylindrical and supported for rotation, with its axis at an angle to the horizontal. Its walls are perforate in part, and it is designed to receive through its higher end the material to be washed and to discharge at its lower end so much of thematerial'as has not in the scrubbin operation passed through the perforate walls. Means are provided for causing washingstreams of water to penetrate the mass of material within the cylinder. The washer or The washer or scrubber is indicated scrubber 1 is inthe drawings shown to be -mounted for rotation, by resting upon spools 3,s0me orall of which may be understood'to be power-driven. The water for washing the material enters the cylinder chamber through apipe 4. Material is supplied to the cylinder by an elevator 5 equipped with buckets. The

elevator scoops material fromthe river bed the upper head of the cylindrical Washer 1.

The cylinder is a compound one and in cludes an inner cylindrical shell, to which the 'arranged, the outerisiconveniently borne by the inner, as upon the posts 8, and, at the up per end, upon an annular diaphragm. 81. The inner shell is throug'houtthe two end regionsl]. and 13 perforate,'and throughout an intermediate portion 12 imperforate. The

outer shell is in its higher portion 71-perforate and in its lower. portion 72 imperfora-te; and the imperforate portions 12 and 72 of'the and delivers itby a suitable chute '6 through two shells are preferably arranged, portion 7 2 surrounding portion 12. V

The perforations in the higher portion 11 of the inner shell are larger than the perforations in the higher portion 71 of the outer shell, and ordinarily the perforations in portion 11 will be smaller than those in the lower portion 13 of the inner shell. Specifically,

the perforations in-portion 11 may be of the order of 1 inches across; those in portion 71, of the order 015% of an'inch (this portion will advantageously be'formed as shown, .of

netting) those of portion 13 may be of the order of 3 inches across. It will be understood that the particular dimensions may vary, to meet particular conditions, and to at ford a product of desired range in grade.

end longitudinallyv for. 7 feet; and theportions 12 and 72, for 6 feet. The lower ends of both shells are openv for the discharge of material.

much at least of the space between the two shells as is defined bythe shell portions 12 and 72, and these pipes are providedwith nozzles adapted to direct jets of water upon material'resting upon the rising walls of the turning shells, as best indicated in Big, TV, 7,

Material dredged from the river bed is fed through chute 6 primarily to the inner shell at its upper end. ,7 The material may be un- -derstood to include, mixedwith the desired sand and gravel, cobbles of larger size, which are not desired, or which to the advantage of further separating operations may be initially separated, and sticky clay and silt which are not desired. 'Clay particularly when present exists in coherent masses, and

these masses in the separating apparatus tend to form balls gathering up and entrapping in their :mass, sand'and smaller pebbles and it is particularly a diflicult problem to dis? sipate and wash out these masses of clay, recovering the desired in them.

The material in its native state entering the portion 11 of the inner cylindrical shell assumes as the washer rotates (counterclockwise, as seen in IV) the position indicated at A in Fig. TV. So spread upon the wall of shell portion "11 it is subjected to streams of water projected from nozzles in pipe section 41. The water may be supplied under a pressure of say, 30 pounds to the square .inch; The material so beat upon by water and tumbled by the rotating cylind'er is broken up, and particles less in diameter than 1 inches escape through the perforations into the portion 71 of the outer shell. The material which so escapes is muddy water (some of the clay and substantially all of the silt being already in suspension) separated sand and pebbles, and the smaller nodules and balls "of clay. So much of the material under treatment as does not so escape through the perforations in shell portion 11, advances as. the washer rotates, to the shell portion 12. v I

Of the material which falls through'the perforations of shell section 11 to the outer shell, the liner particles escape through the -inch meshes. The particles so escaping are sand, small pebbles, and bits of clay of such small size that they are substantially dissipated in their entirety in the further treatment. The-material so escaping is caught below in a hopper 9 and directed into a tank 10. So much of the material passing to the outer cylinder as fails to escape material-s entrapped through the perforate shell portion 71, ad-

vances as the washer rotates, to the shell portion 7 2.

The shell portions 12 and 72 are imperforate, and as the washer rotates the blades with which they are interiorly equipped raise and tumble the material, and as the material is by such means raised and tumbled, it continues to be subject to the washing action of the jets of water, andhere the jets fro-1n r.-

pipes 42 act on the material with-in the outer shell, while the jets from pipe 41 continue to act on the material within the inner shell. The eifect of tumbling and washing in this blind (that is to say, imperforate) T portion of the washer is to complete the dissipation of masses of clay.

From the open lower end of the outer cylinder, sand and pebblesliberated from.

ag lomeration with clay pass to the hopper 9 and thence to tank 10,, and theclay also passes to the tank, but in proper Condition for separation. The masses are broken up and the finely divided clay continues in suspension in the body of water. That isto say the water is muddy.v Thismuddy water is discharged from the tank through an overflow. Similarly in shell. portion 12 the bodies of clay are roken up and the clay goes into suspension in the wash water. The 'terial in the inner shell, however, carries while nothing remains to escape from the.

open end of the inner shell but thelarger cobbles of about 8 inches in diameterv and upwards. These large cobbles .so escaping may be returned to the river bedfor they may be accumulated in a suitable receptac'le 20.- V

A'bucket elevator 21 is arranged to elevate from tank 10 and to discharge into other suitable separating apparatus the sand and smaller pebbles,while the muddy water falls away. The further separating apparatus may include, for example, a revolving cylindrical sieve 22 of familiar construction adapted to elfect separation of the larger pebbles, ranging in size from, say, 11/ inches in diameter to 3 inches, and of the medium-sized pebbles, ranging in size from 1%; of an inchto 1% inches, from the fines. Thelarger pebbles are delivered from the openlower end 23 of sieve 22, the medium-sized pebblesare de:

livered from the lower portion 24 of the per forate side walls, after the fines have escaped through the smaller perforations of the upper portion 25 of the side walls. v

The fines from sieve 22 may in a second and similar revolving sieve 26 be separated into sand of different grades or degrees of fineness.

Referring again to Figs. III and IV, my invention will be seen to involve a division of the mass of material under treatment into a plurality of parts, in this instancetwo parts A and B, severally scrubbed in the two scrubbers constituted by the concentric shell parts 12 and 72 and it will be seen that, in consequence of such division, the scrubbingaction is more effective. The provisionof wings within the blind shell portions 12 and 7 2 greatly increases the scrubbing efiect.

In a divisional and companion application, filed August 8th, 1929, Serial number 384,262, I claim the method of treating material which is herein described.

I claim as my invention:

1. A washer for earthy material including two inclined supports arranged one beneath another, the upper including a sieve portion and an imperforate prolongation beyond the lower end of the sieve portion, and the lower support being arranged to receive material passing through the sieve portion of the upper support, means associated with each support for directing washing streams of water upon the material resting upon it, means for segregating the washed-out burden of the upper support, and means for collecting the washed-out burden of the lower support together with the washing streams.

2. A washer for earthy materials including inner and outer, coaxially arranged, inclined, rotating cylinders, the inner cylinder being perforate in an upper and imperforate in a lower portion, and the outer being arranged to receive material passing through the perforations of the inner cylinder, and being itself provided with an imperforate area, means for directing streams of water upon material resting upon the imperforate areas of the two cylinders, means for segregat ing from the inner cylinder its washed-out burden of coarse material and means for col- 7 lecting the washed-out burden of the outer cylinder together with the washing stream.

3. The washer of claim 2, the cylinders throughout their imperforate extent being provided interiorly with material-tumbling blades. q

4:. A Washer for earthy materials including a plurality of coaxially mounted inclined rotating cylinders, the inner cylinder at its lower end extending beyond the outer cylinder, the inner cylinder in an upper portion being perforated with relatively small perforations and in a lower portion with relatively large perforations, and hav' and the outer cylinder being provided with an upper perforate portion whose perforations are smaller than those of thevupper portion of the inner cylinder, such perforate upper portion of the outercylinder immediately surrounding the upper perforate portion of the inner cylinder, and the outer. cylinder being further provided with a lower imperforate portion, the cylinders ends being open.

In testimony whereof I have hereunto set my hand.

FRANCIS. R. DRAVO.

at their lower 

